1. Field
Example embodiments relate to semiconductor memory devices and methods of fabricating the semiconductor memory devices. Also, example embodiments relate to semiconductor memory devices including recess-type gate electrodes and methods of fabricating the semiconductor memory devices including recess-type gate electrodes.
2. Description of Related Art
With recent development in increasing a speed and miniaturization of semiconductor products, such semiconductor products require more high-integrated and high-speed semiconductor memory devices. Accordingly, instead of related art planar structures, memory devices having three-dimensional structures are being introduced. For example, a semiconductor memory device with a three-dimensional structure has a recess-type control gate electrode extended into a semiconductor substrate.
Such a nonvolatile memory device with a three-dimensional structure has a wide channel region and accordingly has a high operating speed, compared to the related art planar structures. However, the increase in integration of a semiconductor memory with a three-dimensional structure has a limitation. This is because impurity doping regions such as source and drain regions still occupy wide portions in a semiconductor memory device with a three-dimensional structure. Particularly, in a “not and” (NAND) structure semiconductor memory having excellent integration, source regions and drain regions which are positioned alternately has a wide region, which hinders increase of integration.